/**
 * @file
 * IGMP - Internet Group Management Protocol
 *
 */

/*
 * Copyright (c) 2002 CITEL Technologies Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 * 3. Neither the name of CITEL Technologies Ltd nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY CITEL TECHNOLOGIES AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL CITEL TECHNOLOGIES OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 *
 * This file is a contribution to the lwIP TCP/IP stack.
 * The Swedish Institute of Computer Science and Adam Dunkels
 * are specifically granted permission to redistribute this
 * source code.
*/

/*-------------------------------------------------------------
Note 1)
Although the rfc requires V1 AND V2 capability
we will only support v2 since now V1 is very old (August 1989)
V1 can be added if required

a debug print and statistic have been implemented to
show this up.
-------------------------------------------------------------
-------------------------------------------------------------
Note 2)
A query for a specific group address (as opposed to ALLHOSTS)
has now been implemented as I am unsure if it is required

a debug print and statistic have been implemented to
show this up.
-------------------------------------------------------------
-------------------------------------------------------------
Note 3)
The router alert rfc 2113 is implemented in outgoing packets
but not checked rigorously incoming
-------------------------------------------------------------
Steve Reynolds
------------------------------------------------------------*/

/*-----------------------------------------------------------------------------
 * RFC 988  - Host extensions for IP multicasting                         - V0
 * RFC 1054 - Host extensions for IP multicasting                         -
 * RFC 1112 - Host extensions for IP multicasting                         - V1
 * RFC 2236 - Internet Group Management Protocol, Version 2               - V2  <- this code is based on this RFC (it's the "de facto" standard)
 * RFC 3376 - Internet Group Management Protocol, Version 3               - V3
 * RFC 4604 - Using Internet Group Management Protocol Version 3...       - V3+
 * RFC 2113 - IP Router Alert Option                                      - 
 *----------------------------------------------------------------------------*/

/*-----------------------------------------------------------------------------
 * Includes
 *----------------------------------------------------------------------------*/

#include "lwip/opt.h"

#if LWIP_IGMP			/* don't build if not configured for use in lwipopts.h */

#include "lwip/igmp.h"
#include "lwip/debug.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/ip.h"
#include "lwip/inet.h"
#include "lwip/inet_chksum.h"
#include "lwip/netif.h"
#include "lwip/icmp.h"
#include "lwip/udp.h"
#include "lwip/tcp.h"
#include "lwip/stats.h"

#include "string.h"

/*-----------------------------------------------------------------------------
 * Globales
 *----------------------------------------------------------------------------*/

static struct igmp_group *igmp_group_list;
static struct ip_addr allsystems;
static struct ip_addr allrouters;

/**
 * Initialize the IGMP module
 */
void
igmp_init (void)
{
  LWIP_DEBUGF (IGMP_DEBUG, ("igmp_init: initializing\n"));

  IP4_ADDR (&allsystems, 224, 0, 0, 1);
  IP4_ADDR (&allrouters, 224, 0, 0, 2);
}

#ifdef LWIP_DEBUG
/**
 * Dump global IGMP groups list
 */
void
igmp_dump_group_list ()
{
  struct igmp_group *group = igmp_group_list;

  while (group != NULL)
    {
      LWIP_DEBUGF (IGMP_DEBUG,
		   ("igmp_dump_group_list: [%" U32_F "] ",
		    (u32_t) (group->group_state)));
      ip_addr_debug_print (IGMP_DEBUG, &group->group_address);
      LWIP_DEBUGF (IGMP_DEBUG, (" on if %x\n", (int) group->interface));
      group = group->next;
    }
  LWIP_DEBUGF (IGMP_DEBUG, ("\n"));
}
#else
#define igmp_dump_group_list()
#endif /* LWIP_DEBUG */

/**
 * Start IGMP processing on interface
 *
 * @param netif network interface on which start IGMP processing
 */
err_t
igmp_start (struct netif *netif)
{
  struct igmp_group *group;

  LWIP_DEBUGF (IGMP_DEBUG,
	       ("igmp_start: starting IGMP processing on if %x\n",
		(int) netif));

  group = igmp_lookup_group (netif, &allsystems);

  if (group != NULL)
    {
      group->group_state = IGMP_GROUP_IDLE_MEMBER;
      group->use++;

      /* Allow the igmp messages at the MAC level */
      if (netif->igmp_mac_filter != NULL)
	{
	  LWIP_DEBUGF (IGMP_DEBUG, ("igmp_start: igmp_mac_filter(ADD "));
	  ip_addr_debug_print (IGMP_DEBUG, &allsystems);
	  LWIP_DEBUGF (IGMP_DEBUG, (") on if %x\n", (int) netif));
	  netif->igmp_mac_filter (netif, &allsystems, IGMP_ADD_MAC_FILTER);
	}

      return ERR_OK;
    }

  return ERR_MEM;
}

/**
 * Stop IGMP processing on interface
 *
 * @param netif network interface on which stop IGMP processing
 */
err_t
igmp_stop (struct netif * netif)
{
  struct igmp_group *group = igmp_group_list;
  struct igmp_group *prev = NULL;
  struct igmp_group *next;

  /* look for groups joined on this interface further down the list */
  while (group != NULL)
    {
      next = group->next;
      /* is it a group joined on this interface? */
      if (group->interface == netif)
	{
	  /* is it the first group of the list? */
	  if (group == igmp_group_list)
	    {
	      igmp_group_list = next;
	    }
	  /* is there a "previous" group defined? */
	  if (prev != NULL)
	    {
	      prev->next = next;
	    }
	  /* disable the group at the MAC level */
	  if (netif->igmp_mac_filter != NULL)
	    {
	      LWIP_DEBUGF (IGMP_DEBUG, ("igmp_stop: igmp_mac_filter(DEL "));
	      ip_addr_debug_print (IGMP_DEBUG, &group->group_address);
	      LWIP_DEBUGF (IGMP_DEBUG, (") on if %x\n", (int) netif));
	      netif->igmp_mac_filter (netif, &(group->group_address),
				      IGMP_DEL_MAC_FILTER);
	    }
	  /* free group */
	  memp_free (MEMP_IGMP_GROUP, group);
	}
      else
	{
	  /* change the "previous" */
	  prev = group;
	}
      /* move to "next" */
      group = next;
    }
  return ERR_OK;
}

/**
 * Report IGMP memberships for this interface
 *
 * @param netif network interface on which report IGMP memberships
 */
void
igmp_report_groups (struct netif *netif)
{
  struct igmp_group *group = igmp_group_list;

  LWIP_DEBUGF (IGMP_DEBUG,
	       ("igmp_report_groups: sending IGMP reports on if %x\n",
		(int) netif));

  while (group != NULL)
    {
      if (group->interface == netif)
	{
	  igmp_delaying_member (group, IGMP_JOIN_DELAYING_MEMBER_TMR);
	}
      group = group->next;
    }
}

/**
 * Search for a group in the global igmp_group_list
 *
 * @param ifp the network interface for which to look
 * @param addr the group ip address to search for
 * @return a struct igmp_group* if the group has been found,
 *         NULL if the group wasn't found.
 */
struct igmp_group *
igmp_lookfor_group (struct netif *ifp, struct ip_addr *addr)
{
  struct igmp_group *group = igmp_group_list;

  while (group != NULL)
    {
      if ((group->interface == ifp)
	  && (ip_addr_cmp (&(group->group_address), addr)))
	{
	  return group;
	}
      group = group->next;
    }

  /* to be clearer, we return NULL here instead of
   * 'group' (which is also NULL at this point).
   */
  return NULL;
}

/**
 * Search for a specific igmp group and create a new one if not found-
 *
 * @param ifp the network interface for which to look
 * @param addr the group ip address to search
 * @return a struct igmp_group*,
 *         NULL on memory error.
 */
struct igmp_group *
igmp_lookup_group (struct netif *ifp, struct ip_addr *addr)
{
  struct igmp_group *group = igmp_group_list;

  /* Search if the group already exists */
  group = igmp_lookfor_group (ifp, addr);
  if (group != NULL)
    {
      /* Group already exists. */
      return group;
    }

  /* Group doesn't exist yet, create a new one */
  group = memp_malloc (MEMP_IGMP_GROUP);
  if (group != NULL)
    {
      group->interface = ifp;
      ip_addr_set (&(group->group_address), addr);
      group->timer = 0;		/* Not running */
      group->group_state = IGMP_GROUP_NON_MEMBER;
      group->last_reporter_flag = 0;
      group->use = 0;
      group->next = igmp_group_list;

      igmp_group_list = group;
    }

  LWIP_DEBUGF (IGMP_DEBUG,
	       ("igmp_lookup_group: %sallocated a new group with address ",
		(group ? "" : "impossible to ")));
  ip_addr_debug_print (IGMP_DEBUG, addr);
  LWIP_DEBUGF (IGMP_DEBUG, (" on if %x\n", (int) ifp));

  return group;
}

/**
 * Remove a group in the global igmp_group_list
 *
 * @param group the group to remove from the global igmp_group_list
 * @return ERR_OK if group was removed from the list, an err_t otherwise
 */
err_t
igmp_remove_group (struct igmp_group * group)
{
  err_t err = ERR_OK;

  /* Is it the first group? */
  if (igmp_group_list == group)
    {
      igmp_group_list = group->next;
    }
  else
    {
      /* look for group further down the list */
      struct igmp_group *tmpGroup;
      for (tmpGroup = igmp_group_list; tmpGroup != NULL;
	   tmpGroup = tmpGroup->next)
	{
	  if (tmpGroup->next == group)
	    {
	      tmpGroup->next = group->next;
	      break;
	    }
	}
      /* Group not found in the global igmp_group_list */
      if (tmpGroup == NULL)
	err = ERR_ARG;
    }
  /* free group */
  memp_free (MEMP_IGMP_GROUP, group);

  return err;
}

/**
 * Called from ip_input() if a new IGMP packet is received.
 *
 * @param p received igmp packet, p->payload pointing to the ip header
 * @param inp network interface on which the packet was received
 * @param dest destination ip address of the igmp packet
 */
void
igmp_input (struct pbuf *p, struct netif *inp, struct ip_addr *dest)
{
  struct ip_hdr *iphdr;
  struct igmp_msg *igmp;
  struct igmp_group *group;
  struct igmp_group *groupref;

  /* Note that the length CAN be greater than 8 but only 8 are used - All are included in the checksum */
  iphdr = p->payload;
  if (pbuf_header (p, -(s16_t) (IPH_HL (iphdr) * 4))
      || (p->len < IGMP_MINLEN))
    {
      pbuf_free (p);
      IGMP_STATS_INC (igmp.lenerr);
      LWIP_DEBUGF (IGMP_DEBUG, ("igmp_input: length error\n"));
      return;
    }

  LWIP_DEBUGF (IGMP_DEBUG, ("igmp_input: message from "));
  ip_addr_debug_print (IGMP_DEBUG, &(iphdr->src));
  LWIP_DEBUGF (IGMP_DEBUG, (" to address "));
  ip_addr_debug_print (IGMP_DEBUG, &(iphdr->dest));
  LWIP_DEBUGF (IGMP_DEBUG, (" on if %x\n", (int) inp));

  /* Now calculate and check the checksum */
  igmp = (struct igmp_msg *) p->payload;
  if (inet_chksum (igmp, p->len))
    {
      pbuf_free (p);
      IGMP_STATS_INC (igmp.chkerr);
      LWIP_DEBUGF (IGMP_DEBUG, ("igmp_input: checksum error\n"));
      return;
    }

  /* Packet is ok so find an existing group */
  group = igmp_lookfor_group (inp, dest);	/* use the incoming IP address! */

  /* If group can be found or create... */
  if (!group)
    {
      pbuf_free (p);
      LWIP_DEBUGF (IGMP_DEBUG, ("igmp_input: IGMP frame not for us\n"));
      return;
    }

  /* NOW ACT ON THE INCOMING MESSAGE TYPE... */
  switch (igmp->igmp_msgtype)
    {
    case IGMP_MEMB_QUERY:
      {
	/* IGMP_MEMB_QUERY to the "all systems" address ? */
	if ((ip_addr_cmp (dest, &allsystems))
	    && (igmp->igmp_group_address.addr == 0))
	  {
	    /* THIS IS THE GENERAL QUERY */
	    LWIP_DEBUGF (IGMP_DEBUG,
			 ("igmp_input: General IGMP_MEMB_QUERY on \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n",
			  (int) (igmp->igmp_maxresp)));

	    if (igmp->igmp_maxresp == 0)
	      {
		IGMP_STATS_INC (igmp.v1_rxed);
		LWIP_DEBUGF (IGMP_DEBUG,
			     ("igmp_input: got an all hosts query with time== 0 - this is V1 and not implemented - treat as v2\n"));
		igmp->igmp_maxresp = IGMP_V1_DELAYING_MEMBER_TMR;
	      }

	    IGMP_STATS_INC (igmp.group_query_rxed);
	    groupref = igmp_group_list;
	    while (groupref)
	      {
		/* Do not send messages on the all systems group address! */
		if ((groupref->interface == inp)
		    &&
		    (!(ip_addr_cmp
		       (&(groupref->group_address), &allsystems))))
		  {
		    igmp_delaying_member (groupref, igmp->igmp_maxresp);
		  }
		groupref = groupref->next;
	      }
	  }
	else
	  {
	    /* IGMP_MEMB_QUERY to a specific group ? */
	    if (group->group_address.addr != 0)
	      {
		LWIP_DEBUGF (IGMP_DEBUG,
			     ("igmp_input: IGMP_MEMB_QUERY to a specific group "));
		ip_addr_debug_print (IGMP_DEBUG, &group->group_address);
		if (ip_addr_cmp (dest, &allsystems))
		  {
		    LWIP_DEBUGF (IGMP_DEBUG,
				 (" using \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n",
				  (int) (igmp->igmp_maxresp)));
		    /* we first need to re-lookfor the group since we used dest last time */
		    group =
		      igmp_lookfor_group (inp, &igmp->igmp_group_address);
		  }
		else
		  {
		    LWIP_DEBUGF (IGMP_DEBUG,
				 (" with the group address as destination [igmp_maxresp=%i]\n",
				  (int) (igmp->igmp_maxresp)));
		  }

		if (group != NULL)
		  {
		    IGMP_STATS_INC (igmp.unicast_query);
		    igmp_delaying_member (group, igmp->igmp_maxresp);
		  }
	      }
	  }
	break;
      }
    case IGMP_V2_MEMB_REPORT:
      {
	LWIP_DEBUGF (IGMP_DEBUG, ("igmp_input: IGMP_V2_MEMB_REPORT\n"));

	IGMP_STATS_INC (igmp.report_rxed);
	if (group->group_state == IGMP_GROUP_DELAYING_MEMBER)
	  {
	    /* This is on a specific group we have already looked up */
	    group->timer = 0;	/* stopped */
	    group->group_state = IGMP_GROUP_IDLE_MEMBER;
	    group->last_reporter_flag = 0;
	  }
	break;
      }
    default:
      {
	LWIP_DEBUGF (IGMP_DEBUG,
		     ("igmp_input: unexpected msg %x in state %x on group %x on if %x\n",
		      (int) igmp->igmp_msgtype, (int) group->group_state,
		      (int) &group, (int) group->interface));
	break;
      }
    }

  pbuf_free (p);
  return;
}

/**
 * Join a group on one network interface.
 *
 * @param ifaddr ip address of the network interface which should join a new group
 * @param groupaddr the ip address of the group which to join
 * @return ERR_OK if group was joined on the netif(s), an err_t otherwise
 */
err_t
igmp_joingroup (struct ip_addr * ifaddr, struct ip_addr * groupaddr)
{
  err_t err = ERR_VAL;		/* no matching interface */
  struct igmp_group *group;
  struct netif *netif;

  /* make sure it is multicast address */
  LWIP_ERROR ("igmp_joingroup: attempt to join non-multicast address",
	      ip_addr_ismulticast (groupaddr), return ERR_VAL;
    );
  LWIP_ERROR ("igmp_joingroup: attempt to join allsystems address",
	      (!ip_addr_cmp (groupaddr, &allsystems)), return ERR_VAL;
    );

  /* loop through netif's */
  netif = netif_list;
  while (netif != NULL)
    {
      /* Should we join this interface ? */
      if ((netif->flags & NETIF_FLAG_IGMP)
	  &&
	  ((ip_addr_isany (ifaddr)
	    || ip_addr_cmp (&(netif->ip_addr), ifaddr))))
	{
	  /* find group or create a new one if not found */
	  group = igmp_lookup_group (netif, groupaddr);

	  if (group != NULL)
	    {
	      /* This should create a new group, check the state to make sure */
	      if (group->group_state != IGMP_GROUP_NON_MEMBER)
		{
		  LWIP_DEBUGF (IGMP_DEBUG,
			       ("igmp_joingroup: join to group not in state IGMP_GROUP_NON_MEMBER\n"));
		}
	      else
		{
		  /* OK - it was new group */
		  LWIP_DEBUGF (IGMP_DEBUG,
			       ("igmp_joingroup: join to new group: "));
		  ip_addr_debug_print (IGMP_DEBUG, groupaddr);
		  LWIP_DEBUGF (IGMP_DEBUG, ("\n"));

		  /* If first use of the group, allow the group at the MAC level */
		  if ((group->use == 0) && (netif->igmp_mac_filter != NULL))
		    {
		      LWIP_DEBUGF (IGMP_DEBUG,
				   ("igmp_joingroup: igmp_mac_filter(ADD "));
		      ip_addr_debug_print (IGMP_DEBUG, groupaddr);
		      LWIP_DEBUGF (IGMP_DEBUG, (") on if %x\n", (int) netif));
		      netif->igmp_mac_filter (netif, groupaddr,
					      IGMP_ADD_MAC_FILTER);
		    }

		  IGMP_STATS_INC (igmp.join_sent);
		  igmp_send (group, IGMP_V2_MEMB_REPORT);

		  igmp_start_timer (group, IGMP_JOIN_DELAYING_MEMBER_TMR);

		  /* Need to work out where this timer comes from */
		  group->group_state = IGMP_GROUP_DELAYING_MEMBER;
		}
	      /* Increment group use */
	      group->use++;
	      /* Join on this interface */
	      err = ERR_OK;
	    }
	  else
	    {
	      /* Return an error even if some network interfaces are joined */
	/** @todo undo any other netif already joined */
	      LWIP_DEBUGF (IGMP_DEBUG,
			   ("igmp_joingroup: Not enought memory to join to group\n"));
	      return ERR_MEM;
	    }
	}
      /* proceed to next network interface */
      netif = netif->next;
    }

  return err;
}

/**
 * Leave a group on one network interface.
 *
 * @param ifaddr ip address of the network interface which should leave a group
 * @param groupaddr the ip address of the group which to leave
 * @return ERR_OK if group was left on the netif(s), an err_t otherwise
 */
err_t
igmp_leavegroup (struct ip_addr * ifaddr, struct ip_addr * groupaddr)
{
  err_t err = ERR_VAL;		/* no matching interface */
  struct igmp_group *group;
  struct netif *netif;

  /* make sure it is multicast address */
  LWIP_ERROR ("igmp_leavegroup: attempt to leave non-multicast address",
	      ip_addr_ismulticast (groupaddr), return ERR_VAL;
    );
  LWIP_ERROR ("igmp_leavegroup: attempt to leave allsystems address",
	      (!ip_addr_cmp (groupaddr, &allsystems)), return ERR_VAL;
    );

  /* loop through netif's */
  netif = netif_list;
  while (netif != NULL)
    {
      /* Should we leave this interface ? */
      if ((netif->flags & NETIF_FLAG_IGMP)
	  &&
	  ((ip_addr_isany (ifaddr)
	    || ip_addr_cmp (&(netif->ip_addr), ifaddr))))
	{
	  /* find group */
	  group = igmp_lookfor_group (netif, groupaddr);

	  if (group != NULL)
	    {
	      /* Only send a leave if the flag is set according to the state diagram */
	      LWIP_DEBUGF (IGMP_DEBUG, ("igmp_leavegroup: Leaving group: "));
	      ip_addr_debug_print (IGMP_DEBUG, groupaddr);
	      LWIP_DEBUGF (IGMP_DEBUG, ("\n"));

	      /* If there is no other use of the group */
	      if (group->use <= 1)
		{
		  /* If we are the last reporter for this group */
		  if (group->last_reporter_flag)
		    {
		      LWIP_DEBUGF (IGMP_DEBUG,
				   ("igmp_leavegroup: sending leaving group\n"));
		      IGMP_STATS_INC (igmp.leave_sent);
		      igmp_send (group, IGMP_LEAVE_GROUP);
		    }

		  /* Disable the group at the MAC level */
		  if (netif->igmp_mac_filter != NULL)
		    {
		      LWIP_DEBUGF (IGMP_DEBUG,
				   ("igmp_leavegroup: igmp_mac_filter(DEL "));
		      ip_addr_debug_print (IGMP_DEBUG, groupaddr);
		      LWIP_DEBUGF (IGMP_DEBUG, (") on if %x\n", (int) netif));
		      netif->igmp_mac_filter (netif, groupaddr,
					      IGMP_DEL_MAC_FILTER);
		    }

		  LWIP_DEBUGF (IGMP_DEBUG,
			       ("igmp_leavegroup: remove group: "));
		  ip_addr_debug_print (IGMP_DEBUG, groupaddr);
		  LWIP_DEBUGF (IGMP_DEBUG, ("\n"));

		  /* Free the group */
		  igmp_remove_group (group);
		}
	      else
		{
		  /* Decrement group use */
		  group->use--;
		}
	      /* Leave on this interface */
	      err = ERR_OK;
	    }
	  else
	    {
	      /* It's not a fatal error on "leavegroup" */
	      LWIP_DEBUGF (IGMP_DEBUG,
			   ("igmp_leavegroup: not member of group\n"));
	    }
	}
      /* proceed to next network interface */
      netif = netif->next;
    }

  return err;
}

/**
 * The igmp timer function (both for NO_SYS=1 and =0)
 * Should be called every IGMP_TMR_INTERVAL milliseconds (100 ms is default).
 */
void
igmp_tmr (void)
{
  struct igmp_group *group = igmp_group_list;

  while (group != NULL)
    {
      if (group->timer != 0)
	{
	  group->timer -= 1;
	  if (group->timer == 0)
	    {
	      igmp_timeout (group);
	    }
	}
      group = group->next;
    }
}

/**
 * Called if a timeout for one group is reached.
 * Sends a report for this group.
 *
 * @param group an igmp_group for which a timeout is reached
 */
void
igmp_timeout (struct igmp_group *group)
{
  /* If the state is IGMP_GROUP_DELAYING_MEMBER then we send a report for this group */
  if (group->group_state == IGMP_GROUP_DELAYING_MEMBER)
    {
      LWIP_DEBUGF (IGMP_DEBUG,
		   ("igmp_timeout: report membership for group with address "));
      ip_addr_debug_print (IGMP_DEBUG, &(group->group_address));
      LWIP_DEBUGF (IGMP_DEBUG, (" on if %x\n", (int) group->interface));

      igmp_send (group, IGMP_V2_MEMB_REPORT);
    }
}

/**
 * Start a timer for an igmp group
 *
 * @param group the igmp_group for which to start a timer
 * @param max_time the time in multiples of IGMP_TMR_INTERVAL (decrease with
 *        every call to igmp_tmr())
 */
void
igmp_start_timer (struct igmp_group *group, u8_t max_time)
{
  /**
   * @todo Important !! this should be random 0 -> max_time. Find out how to do this
   */
  group->timer = max_time;
}

/**
 * Stop a timer for an igmp_group
 *
 * @param group the igmp_group for which to stop the timer
 */
void
igmp_stop_timer (struct igmp_group *group)
{
  group->timer = 0;
}

/**
 * Delaying membership report for a group if necessary
 *
 * @param group the igmp_group for which "delaying" membership report
 * @param maxresp query delay
 */
void
igmp_delaying_member (struct igmp_group *group, u8_t maxresp)
{
  if ((group->group_state == IGMP_GROUP_IDLE_MEMBER)
      || ((group->group_state == IGMP_GROUP_DELAYING_MEMBER)
	  && (maxresp > group->timer)))
    {
      igmp_start_timer (group, (maxresp) / 2);
      group->group_state = IGMP_GROUP_DELAYING_MEMBER;
    }
}


/**
 * Sends an IP packet on a network interface. This function constructs the IP header
 * and calculates the IP header checksum. If the source IP address is NULL,
 * the IP address of the outgoing network interface is filled in as source address.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
            protocol header; if dest == IP_HDRINCL, p already includes an IP
            header and p->payload points to that IP header)
 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
 *         IP  address of the netif used to send is used as source address)
 * @param dest the destination IP address to send the packet to
 * @param ttl the TTL value to be set in the IP header
 * @param proto the PROTOCOL to be set in the IP header
 * @param netif the netif on which to send this packet
 * @return ERR_OK if the packet was sent OK
 *         ERR_BUF if p doesn't have enough space for IP/LINK headers
 *         returns errors returned by netif->output
 */
err_t
igmp_ip_output_if (struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
		   u8_t ttl, u8_t proto, struct netif *netif)
{
  static u16_t ip_id = 0;
  struct ip_hdr *iphdr = NULL;
  u16_t *ra = NULL;

  /* First write in the "router alert" */
  if (pbuf_header (p, ROUTER_ALERTLEN))
    {
      LWIP_DEBUGF (IGMP_DEBUG,
		   ("igmp_ip_output_if: not enough room for IP header in pbuf\n"));
      return ERR_BUF;
    }

  /* This is the "router alert" option */
  ra = p->payload;
  ra[0] = htons (ROUTER_ALERT);
  ra[1] = 0x0000;		/* Router shall examine packet */

  /* now the normal ip header */
  if (pbuf_header (p, IP_HLEN))
    {
      LWIP_DEBUGF (IGMP_DEBUG,
		   ("igmp_ip_output_if: not enough room for IP header in pbuf\n"));
      return ERR_BUF;
    }

  iphdr = p->payload;

  /* Should the IP header be generated or is it already included in p? */
  if (dest != IP_HDRINCL)
    {
    /** @todo should be shared with ip.c - ip_output_if */
      IPH_TTL_SET (iphdr, ttl);
      IPH_PROTO_SET (iphdr, proto);

      ip_addr_set (&(iphdr->dest), dest);

      IPH_VHLTOS_SET (iphdr, 4, ((IP_HLEN + ROUTER_ALERTLEN) / 4),
		      0 /*tos */ );
      IPH_LEN_SET (iphdr, htons (p->tot_len));
      IPH_OFFSET_SET (iphdr, 0);
      IPH_ID_SET (iphdr, htons (ip_id));
      ++ip_id;

      if (ip_addr_isany (src))
	{
	  ip_addr_set (&(iphdr->src), &(netif->ip_addr));
	}
      else
	{
	  ip_addr_set (&(iphdr->src), src);
	}

      IPH_CHKSUM_SET (iphdr, 0);
#if CHECKSUM_GEN_IP
      IPH_CHKSUM_SET (iphdr,
		      inet_chksum (iphdr, (IP_HLEN + ROUTER_ALERTLEN)));
#endif
    }
  else
    {
      dest = &(iphdr->dest);
    }

#if IP_DEBUG
  ip_debug_print (p);
#endif

  LWIP_DEBUGF (IGMP_DEBUG,
	       ("igmp_ip_output_if: sending to if %x\n", (int) netif));

  return netif->output (netif, p, dest);
}

/**
 * Send an igmp packet to a specific group.
 *
 * @param group the group to which to send the packet
 * @param type the type of igmp packet to send
 */
void
igmp_send (struct igmp_group *group, u8_t type)
{
  struct pbuf *p = NULL;
  struct igmp_msg *igmp = NULL;
  struct ip_addr src = { 0 };
  struct ip_addr *dest = NULL;

  /* IP header + "router alert" option + IGMP header */
  p = pbuf_alloc (PBUF_TRANSPORT, IGMP_MINLEN, PBUF_RAM);

  if (p)
    {
      igmp = p->payload;
      LWIP_ASSERT
	("igmp_send: check that first pbuf can hold struct igmp_msg",
	 (p->len >= sizeof (struct igmp_msg)));
      ip_addr_set (&src, &((group->interface)->ip_addr));

      if (type == IGMP_V2_MEMB_REPORT)
	{
	  dest = &(group->group_address);
	  IGMP_STATS_INC (igmp.report_sent);
	  ip_addr_set (&(igmp->igmp_group_address), &(group->group_address));
	  group->last_reporter_flag = 1;	/* Remember we were the last to report */
	}
      else
	{
	  if (type == IGMP_LEAVE_GROUP)
	    {
	      dest = &allrouters;
	      ip_addr_set (&(igmp->igmp_group_address),
			   &(group->group_address));
	    }
	}

      if ((type == IGMP_V2_MEMB_REPORT) || (type == IGMP_LEAVE_GROUP))
	{
	  igmp->igmp_msgtype = type;
	  igmp->igmp_maxresp = 0;
	  igmp->igmp_checksum = 0;
	  igmp->igmp_checksum = inet_chksum (igmp, IGMP_MINLEN);

	  igmp_ip_output_if (p, &src, dest, IGMP_TTL, IP_PROTO_IGMP,
			     group->interface);
	}

      pbuf_free (p);
    }
  else
    {
      LWIP_DEBUGF (IGMP_DEBUG,
		   ("igmp_send: not enough memory for igmp_send\n"));
    }
}

#endif /* LWIP_IGMP */
